Colored rubber product and method of making same



Patented Jan. 22, 1935 COLORED RUBBER."PRODUGT AND v AME Elmer Croakman; Akron; Ohio; toi

National Aniline & ChemioalComp'anmiInc New York, NQE, acorporation of New-York- 'No'nmw'in .l llicationNovember 192%, Q Q No- 11 Ql'aims'.

This invention relates to the art ofJcoloring, unvulcamized: rubbersnbstances; suchpas rubber, guttaeperchaibalata, synthetic. rubber,.and other solidzmaterials commonly: classed under the term 8 rubber.?;; andftdthe colored, products resulting theretromzior ,comprisingvthe same, both: before and after vulcanization, t

1 Itis; well knownthat under suitable, conditions certain organiczdyes cambe used: for coloring or 10 dyeinmunvulcanized rubber. substances and rub-- ber': compounds or: compositions. As heretofore practicedghowerer, the: organic dyes thus employedhave been incorporatedor compounded in their normal state of oxidation with the raw l5 rubber; orthezrunvulcanized rubber mix, and the resulting; colored product subsequentlyused or treatedrin any, desired; way known to the art. Unvulcanized colored rubber products thus-ob tained have beemordinarily subjected to vulcanization at a suitable. temperature inthe-presence of vulcanizing ingredients and a suitable acceleraton.

In my. copending-application. Serial No. 232,460,

filed: on; event date herewithfor Colored rubber 23; productand method of: making'same, there is described and claimed the coloring: of raw rubber material by addition thereto of a dyestuff in the leucostateand developing the color of the dyestufit by'oxidationr V V I I sot Accordingtto the present inventiomit hasbeen found that when'a: mass, of-t solidunvulcanized. rubber substance and the leuco compound of a dye, or solution of theleuco compound of a dye are:mixed-,,the:leuco compound readily and evenly 35.. disseminates and distributes itself throughout. the; rubber mass,v and upon, exposure of the. mass thus treated to the air or other oxidant, a-colored rubber product is produced. Improved'results. canbe obtained in-the coloring ofsolid rubber 40v and related productsby incorporating or com.-

pounding therewith, in the unvulcanizedistate and-wither without the addition of asubstratum, I and/or a vulcanizing ingredient, and/or an green shade-is produced;

textileiifibries and; other zmateriali: may:; be, memJ- 5- I tioned, the: vat dyes; for. example; the wanthraqnine' one vat) coloringimatters; sand thewindigoidi .colore v ing mattersrandsthe; sulfuradyeszr 'I'he anthrae quinone and, indizoim ivat dyes: uporr solution; or

treatment: with alkaline: hydrosulfite solution. are: l 1 (treduced to the leuco state, whilerthersulfuridyes are reduced: to -the leucmfornr-byi treatment. or

solution inxsodiumzsulfidevor insodiumghydrosul-i fite solutlonst,

- Thev following; ex 7 pleswilliiillustrate-the-Zina 15:

vention, it being; understood-,thatztheinventima is-:- not limited: thereto. :The; parts. are bvrtweightg Example: l-b-To aa-rubben mixhconsistinggof 1 on a warm- :mixing; nfillitlrerevis; slowlv a'dded a at solution cQmpri-singmoneuarter part of} Thional green, 2G3 (Schultz: No.@746,-1 prepared: from 1 phenylamino-44-hydroxyphenylamino ;g naphthalene-W-sulfonim acid h and; sodium; polypercent; sodium sulfides aqueoussolution 'and, 10s: parts of; 'Iurkey red 011 Th6"l1llVl1lCfiXliZQdr mix-4 turerupon exposure toair isicolored; a light greem; shade; :Uporr: being ,cured r in; a 1 mold for '15,;

minutes; at -;a--temperature@ corresponding? to; 35 i lbs steam; pressure (aboutdOB-Ml? C.) ,1; a vulcanizedrubber. ,productahaving'asimilar light B using, im this examplaione; part i of the V Thional green 2G reduced to the leuco state in g place of one-quarter part, a rubber producthaving. adark g-reenshaderis, .obtainedtboth' before andaftervulcanizatlon; 13 1 1 EmampIe-Za-The initiali-materiala-thevspecific conditions and' the nw e u e'are the; same-as given in: Example, 1, except that no-- '1jurkey red Thional green 2G theregisqusedasolution comw prising three-quarters part of Indanthrene blue R (Schultz No. 837) dissolved in 15 parts of 3 to 4 percent alkaline sodium hydrosulfite solution. During the addition of the leuco-dye to the rubber mix, most of the water is evaporated off due to the heat of the mill. The rubber mixture, due to exposure to air, is colored a uniform blue shade ugars/ t which, after vulcanization, produces a product having a similar shade which is fast to light and Indanthrene green B (Schultz; N9,1fla ,--Indan+1 threne violet 2R (Schultz No. 767), lndan'threne-i dark blue BO (Schultz No. 763), etc Instead of the leuco compoundsof thedyesme above examples, a mixturebftWd-Ormor'e of thell leuco compounds of the above dyes or of any bf eomp'ri'ses mixing a solution of the leuco compound of a dye with a solid unvulcanized rubber the leuco derivatives of the reducible dyestuffs of; the same or different series may be used. In'this way various shades and depths of colqp may-be;

obtained in the colored product.

It istoib'e unders'tood 'that ithe rubber can-be compounded with & various iproportions i'of theleuco dye,x.oria-' mixture of different ileuco. dyes, and with or withoutithe presence or additionof a substratum, a dispersing agent for =thei'dye, a vulcanizin'g, agent, an accelerator, or other ingredients employed in-uthemanufacture of unvulcanized or vulcanized rubberL-sproducts and that the order of mixing th'e materials or :com-

pounding the rubbermay' bevaried in'any desired or suitable manner;':"'- w- 1::1' The order in'which'the steps of oxidation of theleuco'dyestufi and vulan'ization'of the rubber are carried out may be varied, so that the leuco:

compound'of the dye may be'oxidized before vulcanization', or, by properly'- adjusting the additional quantity of reducing agent present with the leuco compound, andcarrying out the vulcanization in the absence of air or other oxidant, the oxidation may be prevented from occuring during vulcanization, and produced after canizatiofi;" oi tHe."Steps 6f villcanizationand oxidation may be carried out simu1taheously. 1

It may befurthernoted that instead of Turkey red oil which is used as 'a dispersing agent forthe leuco compound; -enab1ingthe use of less water in the incorporatingsolution/other similarly acting materials may be used.

The term u'nvulcanized rubber substance ihas excludes-liquidor viscous rubber substances such as latex.'- The term"rubber-' material has been used as a generic expression to denote the above solid substances either before 'orafter vulcaniza ti0n I 1 I-claimj 1 1 Z a 1. In a processiof coloring a rubber material, the improvement which comprises *mixing the leuco compound of a dye with a mix"cont'aining a 'solid unvulcanized rubber substance under conditions preventing oxidation of the leucocome pound, oxidizing-the leuco *compound and vulcanizing the rubber substance, 1

2. In a process of coloring rubber, the improvement which comprises mixing the leuco compound of a dye with a mix containing a solid unvulcanized rubber substance under conditions preventing oxidation of the leuco compound, and

simultaneously, oxidizing the leuco. compound and vulcanizingftherubbery 5-.

3. In a process of coloring a r'ubb'er"'material,

,the. improvement which comprises mixing the "leuco compound of a dye with a mix containing .a solid unvulcanizedrubber substance under conditions "pr-eventing oxidation of the leuco com- .poundl vulcanizing the rubber under non- 'o'xidizing conditions and then oxidizing the leuco comp u d-i eoloring rubber material which substance oxidizing the leuco compound contained in the resulting mixture, and vulcanizing the rubber substanceii. i

5. A" process of coloring rubber material which comprises mixing a solution ofwth'e leuco com-L: pound of-a dye witha solid unvulcani'zed-rubber substance, and simultaneously oxidizing the leuco compound contained in the resulting m-ixture'and vulcanizing the rubber substan'ce;f

6. 'A'process of coloring rubber material which comprises mixing a solution of.=.the-1eucocompound of a dye with a solid unvulcanized rubber"- substance, vulcanizing the rubber substance under nonoxidizing conditions and then oxidizing the.

leuco compound product.

canizingfth'e rubbersubstance. r ,1 Y "8; A process of coloring rubber material which comprisesmixing a solution of the leuc'o com pound of a vat dye with a'solidunvulcanizedrubber substance, oxidizing the leucocompoundcon tained in the; resulting mi xture, and vulcanizingi thei'r ubber substance. a 1 1 I '9. A process of coloring rubber material which comprises mixing a solution of the leuco com-- pound of an indigoid vat dyewith solid unvulcanize'dfrubber, -oxidizing the leuco compound contained in theresulting mixture, and v1 '11 canizing the rubber.

310. A pi'QCeSs of coloring rubber material which contained the vulcanizedi;

comprises mixing jasolution of-jthe' leuco compound of an anthraquinone vat dyewith solid 1 unvulcanized rubber, oxidizing the leuco compound contained in the'r'esulting mixture, and

vulcani'zing therubberq v 1 x '11". A process of 'coloringrubber which comprisespr eparingf'a solution of a leuco compound of an anthraquinone vat dye bydissolving the dye in an alkaline solution of a hydrosulfite, mixingthe thus preparedls'olutio'n with a solid unvulcanized rubber substance, [oxidizing the leuco; compound contained in the resultingmixture, and

vulcanizing the rubber substance.-"

:ELMER or. oRoAxMAN. 1 

